From a909f9c6435f0882eac71475b54d53407a450261 Mon Sep 17 00:00:00 2001 From: richardbarry Date: Mon, 14 Feb 2011 10:51:18 +0000 Subject: [PATCH] Continue work on the new timer implementation. Nearly complete. git-svn-id: https://svn.code.sf.net/p/freertos/code/trunk@1294 1d2547de-c912-0410-9cb9-b8ca96c0e9e2 --- Source/include/FreeRTOS.h | 4 + Source/include/timers.h | 9 +- Source/queue.c | 25 ++-- Source/tasks.c | 22 ++- Source/timers.c | 294 ++++++++++++++++++++++---------------- 5 files changed, 205 insertions(+), 149 deletions(-) diff --git a/Source/include/FreeRTOS.h b/Source/include/FreeRTOS.h index a6e1035c4..b19fbaeba 100644 --- a/Source/include/FreeRTOS.h +++ b/Source/include/FreeRTOS.h @@ -181,6 +181,10 @@ typedef portBASE_TYPE (*pdTASK_HOOK_CODE)( void * ); #define INCLUDE_xTaskResumeFromISR 1 #endif +#ifndef configASSERT + #define configASSERT( x ) +#endif + /* The timers module relies on xTaskGetSchedulerState(). */ #if configUSE_TIMERS == 1 diff --git a/Source/include/timers.h b/Source/include/timers.h index 95431e464..7e30f1ce5 100644 --- a/Source/include/timers.h +++ b/Source/include/timers.h @@ -67,11 +67,10 @@ extern "C" { #endif /* IDs for commands that can be sent/received on the timer queue. */ -#define trmCOMMAND_PROCESS_TIMER_OVERFLOW 0 /* For use by the kernel only! */ -#define tmrCOMMAND_START 1 -#define tmrCOMMAND_STOP 2 -#define tmrCOMMAND_CHANGE_PERIOD 3 -#define tmrCOMMAND_DELETE 4 +#define tmrCOMMAND_START 0 +#define tmrCOMMAND_STOP 1 +#define tmrCOMMAND_CHANGE_PERIOD 2 +#define tmrCOMMAND_DELETE 3 /*----------------------------------------------------------- * MACROS AND DEFINITIONS diff --git a/Source/queue.c b/Source/queue.c index 806413071..c08d4c174 100644 --- a/Source/queue.c +++ b/Source/queue.c @@ -1469,20 +1469,27 @@ signed portBASE_TYPE xReturn; void vQueueWaitForMessageRestricted( xQueueHandle pxQueue, portTickType xTicksToWait ) { - /* This function should not be called by application code hence the - 'Restricted' in its name. It is not part of the public API. It is designed - for use by kernel code, and has special calling requirements - it should be - called from a critical section, and then a yield performed after it is - called. Also, the call tree makes use of vListInsert() which should normally - not be called from a critical section - so an assumption is made that the list - being inserted into is empty and therefore the insertion will be fast. */ - - /* Only do anything if there are no message in the queue. */ + /* This function should not be called by application code hence the + 'Restricted' in its name. It is not part of the public API. It is + designed for use by kernel code, and has special calling requirements. + It can result in vListInsert() being called on a list that can only + possibly ever have one item in it, so the list will be fast, but even + so it should be called with the scheduler locked and not from a critical + section. */ + + /* Only do anything if there are no messages in the queue. This function + will not actually cause the task to block, just place it on a blocked + list. It will not block until the scheduler is unlocked - at which + time a yield will be performed. If an item is added to the queue while + the queue is locked, and the calling task blocks on the queue, then the + calling task will be immediately unblocked when the queue is unlocked. */ + prvLockQueue( pxQueue ); if( pxQueue->uxMessagesWaiting == ( unsigned portBASE_TYPE ) 0U ) { /* There is nothing in the queue, block for the specified period. */ vTaskPlaceOnEventListRestricted( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait ); } + prvUnlockQueue( pxQueue ); } #endif diff --git a/Source/tasks.c b/Source/tasks.c index 3e4fb525c..70b629d3f 100644 --- a/Source/tasks.c +++ b/Source/tasks.c @@ -754,7 +754,7 @@ tskTCB *pxTCB = ( tskTCB * ) pxTask; /* This function is not intended to be a public API function and definitely is not for generic use as it assumes pxTask is not the running task and not - suspended, does not remove the task from any event lists it might be + suspended, does not remove the task from any event lists it might be blocked on, and does not take care of mutual exclusion. */ vListRemove( &( pxTCB->xGenericListItem ) ); prvAddTaskToReadyQueue( pxTCB ); @@ -1444,19 +1444,13 @@ void vTaskIncrementTick( void ) /* Tick count has overflowed so we need to swap the delay lists. If there are any items in pxDelayedTaskList here then there is an error! */ + configASSERT( ( listLIST_IS_EMPTY( pxDelayedTaskList ) ) ); + pxTemp = pxDelayedTaskList; pxDelayedTaskList = pxOverflowDelayedTaskList; pxOverflowDelayedTaskList = pxTemp; xNumOfOverflows++; - - #if configUSE_TIMERS == 1 - { - /* The timer service task needs to know to switch its lists - too. */ - xTimerGenericCommand( NULL, trmCOMMAND_PROCESS_TIMER_OVERFLOW, 0, 0 ); - } - #endif - + if( listLIST_IS_EMPTY( pxDelayedTaskList ) != pdFALSE ) { /* The delayed list is empty. Set xNextTaskUnblockTime to the @@ -1756,9 +1750,9 @@ portTickType xTimeToWake; { portTickType xTimeToWake; - /* This function should not be called by application code hence the - 'Restricted' in its name. It is not part of the public API. It is - designed for use by kernel code, and has special calling requirements - + /* This function should not be called by application code hence the + 'Restricted' in its name. It is not part of the public API. It is + designed for use by kernel code, and has special calling requirements - it should be called from a critical section. */ @@ -1769,7 +1763,7 @@ portTickType xTimeToWake; vListInsertEnd( ( xList * ) pxEventList, ( xListItem * ) &( pxCurrentTCB->xEventListItem ) ); /* We must remove this task from the ready list before adding it to the - blocked list as the same list item is used for both lists. This + blocked list as the same list item is used for both lists. This function is called form a critical section. */ vListRemove( ( xListItem * ) &( pxCurrentTCB->xGenericListItem ) ); diff --git a/Source/timers.c b/Source/timers.c index 2a6b8fe0e..c9d592c28 100644 --- a/Source/timers.c +++ b/Source/timers.c @@ -117,25 +117,45 @@ static void prvTimerTask( void *pvParameters ) PRIVILEGED_FUNCTION; * Called by the timer service task to interpret and process a command it * received on the timer queue. */ -static void prvProcessReceivedCommands( portTickType xAssumedTimeNow ) PRIVILEGED_FUNCTION; +static void prvProcessReceivedCommands( void ) PRIVILEGED_FUNCTION; /* - * Insert the timer into either xActiveTimerList1, or xActiveTimerList2, - * depending on if the expire time causes a timer counter overflow. + * Insert the timer into either xActiveTimerList1, or xActiveTimerList2, + * depending on if the expire time causes a timer counter overflow. */ -static void prvInsertTimerInActiveList( xTIMER *pxTimer, portTickType xNextExpiryTime, portTickType xAssumedTimeNow ) PRIVILEGED_FUNCTION; +static void prvInsertTimerInActiveList( xTIMER *pxTimer, portTickType xNextExpiryTime, portTickType xTimeNow ) PRIVILEGED_FUNCTION; /* * An active timer has reached its expire time. Reload the timer if it is an * auto reload timer, then call its callback. */ -static void prvProcessExpiredTimer( portTickType xNextExpireTime, portTickType xAssumedTimeNow ) PRIVILEGED_FUNCTION; +static void prvProcessExpiredTimer( portTickType xNextExpireTime, portTickType xTimeNow ) PRIVILEGED_FUNCTION; /* * The tick count has overflowed. Switch the timer lists after ensuring the * current timer list does not still reference some timers. */ -static void prvSwitchTimerLists( portTickType xAssumedTimeNow ) PRIVILEGED_FUNCTION; +static void prvSwitchTimerLists( portTickType xTimeNow, portTickType xLastTime ) PRIVILEGED_FUNCTION; + +/* + * Obtain the current tick count, setting *pxTimerListsWereSwitched to pdTRUE + * if a tick count overflow occurred since prvSampleTimeNow() was last called. + */ +static portTickType prvSampleTimeNow( portBASE_TYPE *pxTimerListsWereSwitched ) PRIVILEGED_FUNCTION; + +/* + * If the timer list contains any active timers then return the expire time of + * the timer that will expire first and set *pxListWasEmpty to false. If the + * timer list does not contain any timers then return 0 and set *pxListWasEmpty + * to pdTRUE. + */ +static portTickType prvLookForExpiredTimer( portBASE_TYPE *pxListWasEmpty ) PRIVILEGED_FUNCTION; + +/* + * If a timer has expired, process it. Otherwise, block the timer service task + * until either a timer does expire or a command is received. + */ +static void prvProcessTimerOrBlockTask( portTickType xNextExpireTime, portBASE_TYPE xListWasEmpty ) PRIVILEGED_FUNCTION; /*-----------------------------------------------------------*/ @@ -151,7 +171,7 @@ portBASE_TYPE xReturn = pdFAIL; if( xTimerQueue != NULL ) { - xReturn = xTaskCreate( prvTimerTask, ( const signed char * ) "Timer Service", configTIMER_TASK_STACK_DEPTH, NULL, configTIMER_TASK_PRIORITY, NULL ); + xReturn = xTaskCreate( prvTimerTask, ( const signed char * ) "Tmr Svc", configTIMER_TASK_STACK_DEPTH, NULL, configTIMER_TASK_PRIORITY, NULL); } return xReturn; @@ -183,7 +203,7 @@ xTIMER *pxNewTimer; } /*-----------------------------------------------------------*/ -portBASE_TYPE xTimerGenericCommand( xTimerHandle xTimer, portBASE_TYPE xCommandID, portTickType xOptionalValue, portTickType xBlockTime ) +portBASE_TYPE xTimerGenericCommand( xTimerHandle xTimer, portBASE_TYPE xCommandID, portTickType xOptionalValue, portBASE_TYPE *pxHigherPriorityTaskWoken, portTickType xBlockTime ) { portBASE_TYPE xReturn = pdFAIL; xTIMER_MESSAGE xMessage; @@ -197,13 +217,20 @@ xTIMER_MESSAGE xMessage; xMessage.xMessageValue = xOptionalValue; xMessage.pxTimer = ( xTIMER * ) xTimer; - if( xTaskGetSchedulerState() == taskSCHEDULER_RUNNING ) + if( pxHigherPriorityTaskWoken == NULL ) { - xReturn = xQueueSendToBack( xTimerQueue, &xMessage, xBlockTime ); + if( xTaskGetSchedulerState() == taskSCHEDULER_RUNNING ) + { + xReturn = xQueueSendToBack( xTimerQueue, &xMessage, xBlockTime ); + } + else + { + xReturn = xQueueSendToBack( xTimerQueue, &xMessage, tmrNO_DELAY ); + } } else { - xReturn = xQueueSendToBack( xTimerQueue, &xMessage, tmrNO_DELAY ); + xReturn = xQueueSendToBackFromISR( xTimerQueue, &xMessage, pxHigherPriorityTaskWoken ); } } @@ -211,128 +238,155 @@ xTIMER_MESSAGE xMessage; } /*-----------------------------------------------------------*/ -static void prvProcessExpiredTimer( portTickType xNextExpireTime, portTickType xAssumedTimeNow ) +static void prvProcessExpiredTimer( portTickType xNextExpireTime, portTickType xTimeNow ) { xTIMER *pxTimer; - if( listLIST_IS_EMPTY( pxCurrentTimerList ) == pdFALSE ) - { - /* Remove the timer from the list of active timers. */ - pxTimer = ( xTIMER * ) listGET_OWNER_OF_HEAD_ENTRY( pxCurrentTimerList ); - vListRemove( &( pxTimer->xTimerListItem ) ); - - /* If the timer is an auto reload timer then calculate the next - expiry time and re-insert the timer in the list of active timers. */ - if( pxTimer->uxAutoReload == pdTRUE ) - { - /* This is the only time a timer is inserted into a list using - a time relative to anything other than the current time. It - will therefore be inserted into the correct list relative to - the time this task thinks it is now, even if a command to - switch lists due to a tick count overflow is already waiting in - the timer queue. */ - prvInsertTimerInActiveList( pxTimer, ( xNextExpireTime + pxTimer->xTimerPeriodInTicks ), xAssumedTimeNow ); - } + /* Remove the timer from the list of active timers. A check has already + been performed to ensure the list is not empty. */ + pxTimer = ( xTIMER * ) listGET_OWNER_OF_HEAD_ENTRY( pxCurrentTimerList ); + vListRemove( &( pxTimer->xTimerListItem ) ); - /* Call the timer callback. */ - pxTimer->pxCallbackFunction( ( xTimerHandle ) pxTimer ); + /* If the timer is an auto reload timer then calculate the next + expiry time and re-insert the timer in the list of active timers. */ + if( pxTimer->uxAutoReload == pdTRUE ) + { + /* This is the only time a timer is inserted into a list using + a time relative to anything other than the current time. It + will therefore be inserted into the correct list relative to + the time this task thinks it is now, even if a command to + switch lists due to a tick count overflow is already waiting in + the timer queue. */ + prvInsertTimerInActiveList( pxTimer, ( xNextExpireTime + pxTimer->xTimerPeriodInTicks ), xTimeNow ); } + + /* Call the timer callback. */ + pxTimer->pxCallbackFunction( ( xTimerHandle ) pxTimer ); } /*-----------------------------------------------------------*/ static void prvTimerTask( void *pvParameters ) { -portTickType xNextExpireTime, xTimeNow, xFrozenTimeNow; +portTickType xNextExpireTime; +portBASE_TYPE xListWasEmpty; /* Just to avoid compiler warnings. */ ( void ) pvParameters; for( ;; ) { - /* Take a snapshot of the time to use while assessing expiry and auto - reload times. */ - xFrozenTimeNow = xTaskGetTickCount(); - - /* Timers are listed in expiry time order, with the head of the list - referencing the task that will expire first. Obtain the time at which - the timer with the nearest expiry time will expire. If there are no - active timers then just set the next expire time to the maximum possible - time to ensure this task does not run unnecessarily. */ - if( listLIST_IS_EMPTY( pxCurrentTimerList ) == pdFALSE ) - { - xNextExpireTime = listGET_ITEM_VALUE_OF_HEAD_ENTRY( pxCurrentTimerList ); - } - else - { - xNextExpireTime = portMAX_DELAY; - } + /* Query the timers list to see if it contains any timers, and if so, + obtain the time at which the next timer will expire. */ + xNextExpireTime = prvLookForExpiredTimer( &xListWasEmpty ); + + /* If a timer has expired, process it. Otherwise, block this task + until either a timer does expire, or a command is received. */ + prvProcessTimerOrBlockTask( xNextExpireTime, xListWasEmpty ); + + /* Empty the command queue. */ + prvProcessReceivedCommands(); + } +} +/*-----------------------------------------------------------*/ - /* Has the timer expired? This expiry time is relative to the snapshot - of the time taken to be used in this loop iteration - so it doesn't - matter at this point if a tick count overflows here. */ - if( xNextExpireTime <= xFrozenTimeNow ) - { - prvProcessExpiredTimer( xNextExpireTime, xFrozenTimeNow ); - } - else +static void prvProcessTimerOrBlockTask( portTickType xNextExpireTime, portBASE_TYPE xListWasEmpty ) +{ +portTickType xTimeNow; +portBASE_TYPE xTimerListsWereSwitched; + + vTaskSuspendAll(); + { + /* Obtain the time now to make an assessment as to whether the timer + has expired or not. If obtaining the time causes the lists to switch + then don't process this timer as any timers that remained in the list + when the lists were switched will have been processed within the + prvSampelTimeNow() function. */ + xTimeNow = prvSampleTimeNow( &xTimerListsWereSwitched ); + if( xTimerListsWereSwitched == pdFALSE ) { - /* Block this task until the next timer expires, or a command is - received. */ - vTaskSuspendAll(); + /* The tick count has not overflowed, has the timer expired? */ + if( ( xListWasEmpty == pdFALSE ) && ( xNextExpireTime <= xTimeNow ) ) { - /* Has the tick overflowed since a time snapshot was taken? */ - xTimeNow = xTaskGetTickCount(); - if( xTimeNow >= xFrozenTimeNow ) - { - /* Has the expire not still not been met? The tick count - may be greater now than when the time snapshot was taken. */ - if( xNextExpireTime <= xTimeNow ) - { - prvProcessExpiredTimer( xNextExpireTime, xFrozenTimeNow ); - } - else - { - /* The tick count has not overflowed since the time - snapshot, and the next expire time has not been reached - since the last snapshot was taken. This task should - therefore block to wait for the next expire time. */ - vQueueWaitForMessageRestricted( xTimerQueue, ( xNextExpireTime - xTimeNow ) ); - } - } - else - { - /* The tick count has overflowed since the time snapshot - was taken, therefore, the task should not block but continue - with another loop. The command queue should contain a - command to switch lists. */ - } + prvProcessExpiredTimer( xNextExpireTime, xTimeNow ); } - if( xTaskResumeAll() == pdFALSE ) + else { - /* Yield to wait for either a command to arrive, or the block time - to expire. If a command arrived between the critical section being - exited and this yield then the yield will just return to the same - task. */ - portYIELD_WITHIN_API(); + /* The tick count has not overflowed, and the next expire + time has not been reached yet. This task should therefore + block to wait for the next expire time or a command to be + received - whichever comes first. The following line cannot + be reached unless xNextExpireTime > xTimeNow, except in the + case when the current timer list is empty. */ + vQueueWaitForMessageRestricted( xTimerQueue, ( xNextExpireTime - xTimeNow ) ); } + } + } + if( xTaskResumeAll() == pdFALSE ) + { + /* Yield to wait for either a command to arrive, or the block time + to expire. If a command arrived between the critical section being + exited and this yield then the yield will not cause the task + to block. */ + portYIELD_WITHIN_API(); + } +} +/*-----------------------------------------------------------*/ - /* Take a snapshot of the time now for use in this iteration of the - task loop. */ - xFrozenTimeNow = xTaskGetTickCount(); +static portTickType prvLookForExpiredTimer( portBASE_TYPE *pxListWasEmpty ) +{ +portTickType xNextExpireTime; - /* Empty the command queue, if it contains any commands. */ - prvProcessReceivedCommands( xFrozenTimeNow ); - } + /* Timers are listed in expiry time order, with the head of the list + referencing the task that will expire first. Obtain the time at which + the timer with the nearest expiry time will expire. If there are no + active timers then just set the next expire time to 0. That will cause + this task to unblock when the tick count overflows, at which point the + timer lists will be switched and the next expiry time can be + re-assessed. */ + *pxListWasEmpty = listLIST_IS_EMPTY( pxCurrentTimerList ); + if( *pxListWasEmpty == pdFALSE ) + { + xNextExpireTime = listGET_ITEM_VALUE_OF_HEAD_ENTRY( pxCurrentTimerList ); + } + else + { + /* Ensure the task unblocks when the tick count rolls over. */ + xNextExpireTime = ( portTickType ) 0U; + } + + return xNextExpireTime; +} +/*-----------------------------------------------------------*/ + +static portTickType prvSampleTimeNow( portBASE_TYPE *pxTimerListsWereSwitched ) +{ +portTickType xTimeNow; +static portTickType xLastTime = ( portTickType ) 0U; + + xTimeNow = xTaskGetTickCount(); + + if( xTimeNow < xLastTime ) + { + prvSwitchTimerLists( xTimeNow, xLastTime ); + *pxTimerListsWereSwitched = pdTRUE; + } + else + { + *pxTimerListsWereSwitched = pdFALSE; } + + xLastTime = xTimeNow; + + return xTimeNow; } /*-----------------------------------------------------------*/ -static void prvInsertTimerInActiveList( xTIMER *pxTimer, portTickType xNextExpiryTime, portTickType xAssumedTimeNow ) +static void prvInsertTimerInActiveList( xTIMER *pxTimer, portTickType xNextExpiryTime, portTickType xTimeNow ) { listSET_LIST_ITEM_VALUE( &( pxTimer->xTimerListItem ), xNextExpiryTime ); listSET_LIST_ITEM_OWNER( &( pxTimer->xTimerListItem ), pxTimer ); - if( xNextExpiryTime < xAssumedTimeNow ) + if( xNextExpiryTime < xTimeNow ) { vListInsert( pxOverflowTimerList, &( pxTimer->xTimerListItem ) ); } @@ -343,11 +397,16 @@ static void prvInsertTimerInActiveList( xTIMER *pxTimer, portTickType xNextExpir } /*-----------------------------------------------------------*/ -static void prvProcessReceivedCommands( portTickType xAssumedTimeNow ) +static void prvProcessReceivedCommands( void ) { xTIMER_MESSAGE xMessage; xTIMER *pxTimer; -portBASE_TYPE xSwitchListsOnExit = pdFALSE; +portBASE_TYPE xTimerListsWereSwitched; +portTickType xTimeNow; + + /* In this case the xTimerListsWereSwitched parameter is not used, but it + must be present in the function call. */ + xTimeNow = prvSampleTimeNow( &xTimerListsWereSwitched ); while( xQueueReceive( xTimerQueue, &xMessage, tmrNO_DELAY ) != pdFAIL ) { @@ -369,7 +428,7 @@ portBASE_TYPE xSwitchListsOnExit = pdFALSE; { case tmrCOMMAND_START : /* Start or restart a timer. */ - prvInsertTimerInActiveList( pxTimer, xAssumedTimeNow + pxTimer->xTimerPeriodInTicks, xAssumedTimeNow ); + prvInsertTimerInActiveList( pxTimer, xTimeNow + pxTimer->xTimerPeriodInTicks, xTimeNow ); break; case tmrCOMMAND_STOP : @@ -379,7 +438,7 @@ portBASE_TYPE xSwitchListsOnExit = pdFALSE; case tmrCOMMAND_CHANGE_PERIOD : pxTimer->xTimerPeriodInTicks = xMessage.xMessageValue; - prvInsertTimerInActiveList( pxTimer, ( xAssumedTimeNow + pxTimer->xTimerPeriodInTicks ), xAssumedTimeNow ); + prvInsertTimerInActiveList( pxTimer, ( xTimeNow + pxTimer->xTimerPeriodInTicks ), xTimeNow ); break; case tmrCOMMAND_DELETE : @@ -387,39 +446,32 @@ portBASE_TYPE xSwitchListsOnExit = pdFALSE; just free up the memory. */ vPortFree( pxTimer ); break; - - case trmCOMMAND_PROCESS_TIMER_OVERFLOW : - /* Hold this pending until all the other messages have been - processed. */ - xSwitchListsOnExit = pdTRUE; - break; default : /* Don't expect to get here. */ break; } } - - if( xSwitchListsOnExit == pdTRUE ) - { - prvSwitchTimerLists( xAssumedTimeNow ); - } } /*-----------------------------------------------------------*/ -static void prvSwitchTimerLists( portTickType xAssumedTimeNow ) +static void prvSwitchTimerLists( portTickType xTimeNow, portTickType xLastTime ) { portTickType xNextExpireTime; xList *pxTemp; - /* The tick count has overflowed. The timer lists must be switched. - If there are any timers still referenced from the current timer list - then they must have expired and should be processed before the lists + /* Remove compiler warnings if configASSERT() is not defined. */ + ( void ) xLastTime; + + /* The tick count has overflowed. The timer lists must be switched. + If there are any timers still referenced from the current timer list + then they must have expired and should be processed before the lists are switched. */ while( listLIST_IS_EMPTY( pxCurrentTimerList ) == pdFALSE ) { xNextExpireTime = listGET_ITEM_VALUE_OF_HEAD_ENTRY( pxCurrentTimerList ); - prvProcessExpiredTimer( xNextExpireTime, xAssumedTimeNow ); + configASSERT( ( xNextExpireTime >= xLastTime ) ); + prvProcessExpiredTimer( xNextExpireTime, xTimeNow ); } pxTemp = pxCurrentTimerList; -- 2.39.5